The present invention relates to a fuel injection system for an internal combustion engine, in particular a diesel engine, having at least two cylinders, the fuel injection system having at least two actuator elements and at least one actuator element being assigned to each cylinder in order to inject fuel into the cylinder. Furthermore, the present invention relates to a method for operating a fuel injection system of this kind.
The object of the present invention is to improve the injection behavior of a fuel injection system of this kind and to simplify a fuel injection system of this kind.
According to the present invention, this object is achieved via a fuel injection system for an internal combustion engine, in particular a diesel engine, having at least two cylinders, according to claim 1, and via a method according to claim 17. Herein, the fuel injection system has at least two actuator elements, at last one actuator element for injecting fuel into the system being assigned to each cylinder, and the fuel injection system having an injection control circuit to perform monitoring and/or to resolve conflicts in triggering of the actuator elements. The actuator elements are piezoelectric elements or solenoid valves.
Furthermore, according to the present invention, this object is achieved via a fuel injection system for an internal combustion engine, in particular a diesel engine, having at least two cylinders, according to claim 4 and via a method according to claim 18. Herein, the fuel injection system has at least two piezoelectric elements, at least one piezoelectric element for injecting fuel into the cylinder via charging or discharging of the piezoelectric element being assigned to each cylinder, the piezoelectric elements being essentially directly electrically connected to one another on at least one side, and the fuel injection system having an injection control system for monitoring whether one piezoelectric element is charged if the other piezoelectric element is to be charged or discharged. Herein, it is advantageous if both piezoelectric elements are arranged on one actuator bank.
Furthermore, according to the present invention, this object is achieved via a fuel injection system for an internal combustion engine, in particular a diesel engine, having at least two cylinders, the fuel injection system having at least two piezoelectric elements, and at least one piezoelectric element for injecting fuel into the cylinder via charging or discharging of the piezoelectric element being assigned to each cylinder, both piezoelectric elements being arranged on one actuator bank, and the fuel injection system having an injection control system for monitoring whether a piezoelectric element is charged if the other piezoelectric element is to be charged or discharged.
Furthermore, according to the present invention, this object is achieved via a fuel injection system for an internal combustion engine, in particular a diesel engine, having at least two cylinders, according to claim 5 and via a method according to claim 19. Herein, the fuel injection system has at least two piezoelectric elements, at least one piezoelectric element for injecting fuel into the cylinder via charging or discharging of the piezoelectric element being assigned to each cylinder, a single supply unit for charging or discharging the piezoelectric element being assigned to the piezoelectric elements, and the fuel injection system having an injection control system for monitoring possible overlap of a time interval during which one piezoelectric element is to be charged or discharged with a time interval during which the other piezoelectric element is to be charged or discharged. Herein, it is advantageous if the two piezoelectric elements are arranged on different actuator banks. According to an advantageous embodiment of the present invention, the injection control system also monitors whether one piezoelectric element is charged if the other piezoelectric element is to be charged or discharged if piezoelectric elements are arranged on one actuator bank or the piezoelectric elements are essentially directly electrically connected to one another on at least one side.
Furthermore, according to the present invention, this object is achieved via a fuel injection system for an internal combustion engine, in particular a diesel engine, having at least two cylinders, the fuel injection system having at least two piezoelectric elements and at least one piezoelectric element for injecting fuel into the cylinder via charging or discharging of the piezoelectric element being assigned to each cylinder, the two piezoelectric elements being arranged on different actuator banks and the fuel injection system having an injection control circuit for monitoring possible overlap of a time interval during which one piezoelectric element is to be charged or discharged with a time interval during which the other piezoelectric element is to be charged or discharged. According to an advantageous embodiment of the present invention, the injection control system also monitors whether one piezoelectric element is charged if the other piezoelectric element is to be charged or discharged if piezoelectric elements are arranged on one actuator bank or the piezoelectric elements are essentially directly electrically connected to one another on at least one side.
According to a further advantageous embodiment of the present invention, injection of fuel in a given injection cycle is carried out via at least two injections, different priorities being assigned to the at least two injections.
According to a further advantageous embodiment of the present invention, injection of fuel is carried out via one main injection and at least one pilot injection prior to the main injection, more fuel being injected into the cylinder via the main injection than via the pilot injection, and the main injection being assigned higher priority than the pilot injection.
According to a further advantageous embodiment of the present invention, injection of fuel is carried out via one main injection and two pilot injections prior to the main injection, namely an earlier and a later pilot injection, one pilot injection being assigned higher priority than the other pilot injection, and it being possible for these priorities to be dependent on the operating point.
According to a further advantageous embodiment of the present invention, injection of the fuel is carried out via at least one main injection and one secondary injection following the main injection, more fuel being injected into the cylinder via the main injection than via the secondary injection, and higher priority being assigned to the main injection than to the secondary injection.
According to a further advantageous embodiment of the present invention, the priorities of the pilot injections and secondary injections are assigned based on the operating point.
According to a further advantageous embodiment of the present invention, the injection having the lower priority is shortened or shifted to such an extent that one piezoelectric element is not charged if the other piezoelectric element is to be charged or discharged. It is advantageous that this is only carried out if both piezoelectric elements are assigned to one actuator bank or if the piezoelectric elements are at least essentially directly electrically connected on at least one side.
If the actuator elements are embodied as solenoid valves, it is advantageous if the injection having the lower priority is shortened to such an extent that no current flows through one solenoid valve if current is flowing through the other solenoid valve.
Shortening of the injection having lower priority also includes shortening to 0, i.e., elimination of the injection if this is necessary.
According to a further advantageous embodiment of the present invention, the injection having the lower priority is shifted to such an extent that the time interval during which a piezoelectric element is to be charged or discharged does not overlap with the time interval during which the other piezoelectric element is to be charged or discharged. It is advantageous that this is only carried out if the two piezoelectric elements are assigned to different actuator banks and if a single supply unit for charging or discharging is assigned to both piezoelectric elements.
According to a further advantageous embodiment of the present invention, the injection having the lower priority is delayed to such an extent that the time interval during which one piezoelectric element is to be charged or discharged does not overlap with the time interval during which the other piezoelectric element is to be charged or discharged. It is advantageous that this is only carried out if the two piezoelectric elements are parts of different actuator banks and a single supply unit for charging and discharging is assigned to both piezoelectric elements.
According to a further advantageous embodiment of the present invention, the injection having the lower priority is shortened to such an extent that the time interval during which one piezoelectric element is to be charged or discharged does not overlap the time interval during which the other piezoelectric element is to be charged or discharged. It is useful that this only happens if both piezoelectric elements are parts of different actuator banks and a single supply unit for charging or discharging is assigned to both piezoelectric elements.
According to a further advantageous embodiment of the present invention, the earlier pilot injection is delayed by the same amount of time as the later pilot injection.
Further advantages and details are set forth in the description of exemplary embodiments below: